Texture and Mechanical Properties of ECA-Pressed Ti

To study the effect of grain size on texture and tensile properties of equal channel angular pressed commercially pure Ti, specimens were made to have the grain size ranging from 4 m to 60 m with the severe plastic deformation followed by recrystallization annealing. In this initial condition all the specimens exhibited a strong bimodal split basal texture. During subsequent repressing at 350°C, the texture pattern became randomized through crystal rotations, the phenomenon being more pronounced in coarse-grained specimens. The microstructure of deformed specimens, as examined by electron back scattered diffraction, showed formation of mechanical twins and microstructural inhomogeneity in the coarse-grained specimens. The room temperature tensile properties of the re-pressed specimens showed that the yield strength was remarkably enhanced regardless of the grain size whereas the elongation was reduced as compared to the initial condition, particularly in coarse-grained specimen. It was concluded that microstructural refinement during the severe plastic deformation was the main cause of the improved yield strength while the twinning and microstructural inhomogeneity were responsible for the texture randomization and the impaired ductility.